Piston expander



NOV.'21, 1939. PHlLUPs I 2.180,428

FIST ON EXPANDER Filed Oct. 29, 1938 INVENTOR.

ATTORNEYS Patented Nov. 21, 193% PISTON EXPANDER Harold P. Phillips,Hastings, Mich., assignor to Hastings Manufacturing Company, Hastings,

Mich.

Application October 29, 1938, Serial No. 237,686

7 Claims.

The main objects of my invention are:

First, to provide a novel expander for pistons of the type having askirt slot therein running only partly of the length of the skirt or noslot.

Second, to provide an expander for expanding the dimension of the pistonat 90 to the wrist pin bearing to force the piston into an oval shape ora shape having an increased amount of oval.

Third, to provide a piston expander of the type described which is verysimple to install without extensive alteration of the piston.

Fourth, to provide an expander of the type described which isexceedingly inexpensive, being formed of inexpensive material and by afew simple manufacturing operations.

Further objects relating to details and economies of my invention willdefinitely appear from the description to follow. The invention isdefined in the claims.

A structure embodying the features of my invention is illustrated in theaccompanying drawing, wherein: V

Fig. 1 is a view in vertical longitudinal section through an internalcombustion engine piston, illustrating one embodiment of the expander ofmy invention in operative relation thereto.

Fig. 2 is a view illustrating the piston expander of my invention in theform which it takes when inserted in a piston the relaxed or unsprungposition of the expander being indicated by dotted lines.

Fig. 3 is a view in section similar to Fig. 1, illustrating a slightlymodified embodiment of the expander of my invention in a somewhatdifferent type of piston from that of Fig. 1.

Fig. 4 is a view similar to Figs. 1 and 3, illustrating a still furtherembodiment of my invention.

Fig. 5 is a View similar to Figs. 1, 3, and 4, illustrating a stillfurther form of expander contemplated by my invention.

Fig. 6 is a fragmentary view in section on line 6-5 of Fig. 5, furtherillustrating details of con- .struction of that embodiment.

On certain types of piston, it is customary to provide a generallyaxially disposed skirt slot which extends only partially of the lengthof the piston skirt, or else the slot is short and has both ends closed.Still other types of pistons have no skirt slots. In order to eliminatepiston rock and slap in worn cylinders, it is usual to expand the skirtof the piston by inserting an expander in the slot; however, in pistonsof the variety which have either no skirt slot or an incomplete one,this is impossible or extremely difiicult without forcing the pistonsinto an objectionably' oval shape. The herein described piston expanderis especially designed for such an adaptation, although it will beapparent that it is also adapted for use in any piston, even oneprovided withv a full length slot. Generally speaking, the

expander of my invention is in the form of a U-shaped' spring elementhaving the free ends thereof secured to the piston skirt at points 90from the wrist pin bearings, whereby an effective outward thrust normalto the said bearings is obtained, so that the dimension across thepiston at 90 to the wrist pin bearings is increased to take up pistonrock and slap.

Referring to the drawing, the reference numeral 1 in each of the figuresdesignates an internal combustion engine piston which, as has beenpointed out, may be of the type having an incomplete skirt slot i. e.,one not extending to the edge of the skirt, or no slot at all or theusual full length slot, my invention being particularly devised for usein the case of a piston having an incomplete slotor none at all. Thepiston illustrated is of the thin walled skirt no-slot type. Theexpander, which is indicated by the reference numeral 2, is generallyU-shaped in form and is made of round spring wire of a diametersufficient to produce the desired spring expansive force. The expanderconsists of a curved bight portion 3 and a pair of longitudinal legportions 6, each, in the embodiment of Fig. 1, terminating in outturnedlugs 5 receivable in holes 6 drilled in the piston skirt for thatpurpose at 90 from the wrist pin bearings 6|.

In the form illustrated in Figs. 1 and 2, it will be observed that theoutline of the expander is made up, in fact, of a plurality of smoothlyconverging curves, the bight 3 being of one radius of curvature whilethe leg portions 4 are of a greater radius of curvature. As a matter offact, in the actual expander, no one of the bight or leg portions is ofa uniform circular curvature and it is necessary to form the expander byproviding a plurality of continuously changing outline. I therefore donot wish to be restricted to an element having any particular type ofourvilinear configuration except as limited by the appended claims.

The leg portions 4 are offset inwardly at I prior to being bentoutwardly at the lugs 5, so that the portion of the skirt on which theexpansive action of the expander 2 is exerted is clearly defined andlocalized along a definite length of the legs thereof.

In Fig. 3, I illustrate an expander which is generally similar in formand disposition with respect to the piston to that illustrated in Fig.1, being, however, characterized by a somewhat more exaggerated inwardoffsetting of the legs at 8 to space the points of thrust engagement 9from the points of securement from the outwardly disposed lugs 10 and asomewhat more uniform curvature.

In Fig. 4,'the expander has leg portions II which are generallyrectilinear and integrally connected to the curvilinear bight portionI2.

The lugs I3 for securing the expander to the piston are formed in a dieby embossing the material of the expander to provide the aforesaidradially outwardly projecting lugs.

5 In Figs. 5 and 6, the expander is generally similar in form to that ofEigs. 1, 2, and 3, having curved leg portions l4, and it is similar toall of the foregoing embodiments in that it is of a U-shaped outline,however the extremities of the leg portions l4 are conformed into smallcircles or coils [5 bearing against the sides of the piston andterminate in the outwardly disposed lugs Hi.

The foresaid circular bearing portions lend.

somewhat to the stability of the expander in 5 installed position andare of advantage in distributing the thrust over larger areas in pistonshaving extremely thin walled skirts.

In actual practice, I have found it desirable to use an expander springwire which is plated to resist acid attacks from certain conditionswhich sometimes occur in internal combustion engines. Experience hasshown that many piston expanders have been broken by hydrogenembrittlement brought about by acid present in the lubricant, and Ithereby contemplate an appropriate treatment of my expander to resistthis condition.

I have illustrated and described my improvements in embodiments whichare very practical.

I have not attempted to illustrate or describe other embodiments oradaptations as it is believed this enclosure will enable those skilledin the art to embody or adapt my improvements as may be desired.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

, 1. An expander for the skirt of an internal combustion engine piston,comprising a U-shaped expanding member of circular section having acontinuously curved bight portion and curved leg portions merging withsaid bight portion, said leg portions being ofiset radially inwardlythen outwardly to provide lugs for mounting the expander on a pistonskirt provided with diametrically opposed holes to receive the lugs,said radial inward offsetting of the leg portion defining a sectionthereof spaced substantially from said lugs for thrust engagement withthe skirt at points spaced substantially above the lowermost edge of theskirt and said lug receiving holes.

2. An expander for the skirt of an internal combustion engine piston,comprising a U-shaped expanding member of circular section having acontinuously curved bight portion and curved leg portions merging withsaid bight portion, said leg portions being offset radially outwardly toprovide lugs for mounting the expander on a piston skirt provided withdiametrically opposed holes to receive the lugs, said leg portions beingcurved for thrust engagement with the skirt at points spacedsubstantially above the lowermost edge of the skirt and above said lugreceiving holes.

3. In combination, a piston having a skirt provided with a continuousuninterrupted lower annular edge, and an expander for the skirtcomprising a U-shaped expanding member having a continuously curvedbight portion and leg portions smoothly merging with said bight portion,

- said leg portions being ofiset radially inwardly then outwardly toprovide elements for mounting the expander in the piston skirt which isprovided with means for receiving the elements, said radial inwardoffsetting of the leg portion defining a section thereof spacedsubstantially from said lugs for thrust engagement with the skirt atpoints spaced substantially above said lowermost edge and above thepoints of engagement of said elements with the skirt.

4. In combination, a piston having a skirt provided with a continuousuninterrupted lower annular edge, and an expander for theskirtcomprising a U-shaped expanding member having a continuously curvedbight portion and leg portions smoothly merging with said bight portion,said leg portions being offset radially outwardly to provide elementsfor mounting the expander in the piston skirt which is provided withmeans for receiving the elements, said leg portions being curved forengagement with said skirt at points substantially above the said edgeand above the points of engagement of the elements with the skirt.

5. In combination, an internal combustion engine piston comprising askirt having a continuous uninterrupted lower edge and a pair of wristpin bearings, and an expander for the skirt comprising a generallyU-shaped expander member of round spring stock, said member having legsprovided with bearing portions and terminating in outwardly disposedlugs adapted to engage in the skirt, said bearing portions being spacedsubstantially from said lugs to engage and exert radial thrust on saidskirt at points spaced substantially above said engine and the points ofengagement of the lugs with the skirt, said expander being compressedand inserted in said skirt and in operative position being disposed atto a. line through the wrist pin bearings of the piston.

6. In combination, an internal combustion engine piston having a skirtwhich is continuous and uninterrupted at its lower edge and is providedwith a pair of opposed holes, said holes being alined at 90 to avertical plane through the wrist pin bearings of the piston, and anexpander for said skirt comprising a generally U-shaped spring member,said member having the legs thereof oiIset inwardly to define a skirtengaging section spaced substantially from the ends of the legs and thenradially outwardly to provide lugs engageable in saidholes, said skirtengaging section engaging and exerting radial thrust on the skirt atpoints spaced substantially from the lower edge thereof and from saidholes whereby to exert deforming action on the piston approximatelymidway of the height thereof.

7. An expander for the skirt of an internal combustion engine piston,comprising a U-shaped expanding member having a curved bight portion andlegs merging with said bight portion, said legs being offset radiallyoutwardly to provide lugs for engaging and mounting the expander on thepiston skirt, said legs being formed between said lugs and bight portionfor thrust engagement with the skirt at points spaced substantiallyabove the lowermost edge of the skirt, and abovethe points on said skirtat which said lugs engage the same.

HAROLD P. PHILLIPS.

